K8SSAND-1636 ⁃ Allow the Cassandra DC name to be different than the CassandraDatacenter name

[jsanda]

Depends on

• Support DC names containing spaces for replication jvm opts management-api-for-apache-cassandra#242

What is missing?
The DC name as stored in Cassandra is always configured to be the same as the CassandraDatacenter name. We need to be able to specify a different name for the DC as stored in Cassandra.

Why do we need it?
This is needed in k8ssandra-operator to avoid naming collisions. See k8ssandra/k8ssandra-operator#615.

This can be supported pretty easily with a small change in the GetConfigAsJSON method (see here) by allowing properties under the datacenter-info key to be overridden. I will try to include a unit test for good measure.

Environment

• Cass Operator version:

  v1.11.0

  **Anything else we need to know?**:

Update

After discussing this offline, we want to apply the same strategy as what's been done with cluster name overrides in k8ssandra-operator:

• The cassdc CRD will get a new DcName field which will allow name overrides that aren't compliant with Kubernetes object names
• This name will be passed as is to cass-config-builder
• It will be sanitized to be made compliant with kubernetes names and labels, and will be used to name and label all subresources. Selectors will be modified accordingly.

In a nutshell, a new method will be created in the cassdc api looking as follows:

...
type CassandraDatacenterSpec struct {
...
...
  DcName string `json:"dcName,omitempty"`
...
}

// SanitizedName returns a sanitized version of the name returned by CassDcName()
func (in *CassandraDatacenter) SanitizedName() string {
	return CleanupForKubernetes(in.CassDcName())
}

// CassDcName returns the Cassandra DC name override if it exists,
// otherwise the cassdc object name.
func (in *CassandraDatacenter) CassDcName() string {
	if in.Spec.Cassandra.DcName != "" {
		return in.Spec.DcName
	}
	return in.Name
}

Wherever the cassdc.Name was previously use, we'll have to use cassdc.SanitizedName() instead, unless we want to refer directly to the cassdc object.

┆Issue is synchronized with this Jira Task by Unito
┆friendlyId: K8SSAND-1636
┆priority: Medium